Most state-of-the-art rowing machines allow oarsmen to simulate motions comparable to ones found when rowing in racing shells. To impart resistance to the rower's physical effort, some rowing machines deploy hydraulic rams (U.S. Pat. No. 5,104,363). However, the most successful ones, in terms of their ability to simulate rowing in boats, deploy an adjustable fluid pump. In certain embodiments, the pump moves air (U.S. Pat. No. 5,382,210) and in the other, the pump moves liquid water (U.S. Pat. No. 4,884,800). Regardless of the type of fluid, all said pumps comprise flywheels. The purpose of moving a fluid through a pump is to simulate an oar drag through water. The purpose of the integrated flywheel is to simulate a boat's inertia.
The beneficial effects of deploying flywheels on rowing machines relate to the flywheel absorbing the user's energy. Since the moment of inertia of a flywheel is constant, the added energy manifests as the flywheel's rotational motion. As this motion simulates that of a gliding boat, the torque resisting a rower suddenly changing the flywheel's rotational velocity is analogous to the force resisting a rower changing the speed of a moving boat.
The problem in using flywheels on rowing machines relates to how a rower applies his force to it. On other type of exercise devices, the combined user's motions tend to be synchronous to the moving flywheel. For example, peddling an exercise bicycle involves moving the feet in a circular motion, synchronous with its flywheel's rotation. In contrast, on a rowing machine, a rower engages the flywheel only during the power portion of the rowing strokes. Furthermore, at the beginning of the power phase of a stroke, the rower handle's velocity is zero, asynchronous to the already moving flywheel.
To engage the moving flywheel, a rower has to catch up to it at the beginning of the power phase of all but the first stroke during every practice. In addition, reconnecting with the moving flywheel becomes more difficult as the flywheel moves faster during more intensive exercise. In an effort to catch up to the flywheel, rowers tend to jerk their shoulders and forearms. The additional shoulder and forearm movement is not ideal and it is contrary to the proper rowing form. More importantly, rowing in such a way can also cause back injury.
In order to retain the flywheel's benefits and at the same time avoid its adverse effects, it is best to replace it with a more optimal device. To that end, this invention focuses on replacing not just the flywheel, but also the fluid pump comprising a flywheel. An embodiment of this invention comprises an electric motor/generator and the motor's control means. Alternatively, the motor can also be substituted with a linear acting solenoid.
Regardless of a given embodiment, the focus of this invention is to eliminate the need for rowers to catch up to the moving flywheel at the beginning of the power phase of every stroke. That is, the primary goal of this invention is to eliminate any backlash between the motion of the rower's handle and the motion of the resistance imparting device. The additional benefit of deploying electric motors or solenoids is that in certain embodiments, this invention can also produce the handle pressure into the back of the rower's palms, at the beginning of the power phase of a rowing stroke. This pressure is similar to the pressure experienced by rowers when rowing in real boats and inserting the oar blade into the moving water.